JPH04187547A - Device for preparing hermetic-coated optical fiber - Google Patents

Abstract

PURPOSE:To enable the continuous coating of an optical fiber for a long period and improve the productivity of the coated optical fiber by disposing a gas phase removal mechanism for removing carbon particles, etc., deposited on the inner wall of a reaction vessel in a hermetic-coated optical fiber preparation device for forming a thin coating layer on the optical fiber by a chemical gas phase deposition method using a carbonic raw material gas fed into the reaction vessel. CONSTITUTION:A high temperature optical fiber 2 spun is fed into a reaction vessel 1, and the optical fiber 2 is subjected to a thermochemical reaction e.g. by a chemical gas phase deposition method using a carbonic raw material gas charged between a raw material gas-charging pipe 3 and a reaction waste gas-discharging pipe 6 to form a hermetic coat on the optical fiber. The gas phase-produced particle layer of carbon particles, etc., adhered to the inner wall of the reaction vessel is oxidized with oxygen gas fed into a part 9 through a small hole 8, changed into gases such as CO2, and subsequently discharged together with waste gases from a reaction waste gas-discharging pipe 6.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an apparatus for mass-producing hermetic coated optical fibers.

[Conventional technology]

A hermetic coat on an optical fiber is effective as a means for preventing outside air such as water and hydrogen from entering the optical fiber. The coating method is a chemical vapor deposition method (CVD) in which a carbon-based raw material gas is chemically reacted to deposit a coat made of carbon or the like on the fiber surface.
Law! 1. It is advantageous in terms of film speed and film quality. Conventionally, as such technology, for example, the US patent rate is 4.7
90,625 or European patent application rate 308.
There is a manufacturing device as shown in No. 143. Such a type of reaction vessel is typical, and the spun high-temperature optical fiber is hermetically coated by a thermal chemical reaction between the raw material gas inlet and outlet in the reaction vessel.

[The problem that the invention tries to solve! ! ]

Conventionally, in such devices, solid particles such as carbon particles generated in the gas phase adhere to the inner wall of the reaction vessel, and when a long coating is attempted, they gradually accumulate, blocking the reaction vessel and causing wires. There was a problem that it became impossible to continue the pull. Therefore, unless such problems are solved, learning habits will not improve and productivity will not be increased.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present inventors have made extensive studies and have provided a hermetic coated optical fiber manufacturing apparatus with a mechanism for removing the solid particle layer deposited on the inner wall of the reaction vessel. The inventors have discovered that the accumulation of the solid particle layer can be eliminated, and have completed the present invention. That is, the present invention: (1) After an optical fiber preform is melted and spun into a bare fiber in a drawing furnace, the bare fiber is introduced into a reaction vessel, and a carbon-based raw material gas is introduced into the reaction vessel. Introduced onto the bare fiber by chemical vapor deposition! In an apparatus for manufacturing a hermetic coated optical fiber coated with a III coating layer, gas phase adhering to the inner wall of the reaction vessel? ! : Provides an apparatus for manufacturing a hermetic coated optical fiber having a mechanism for removing formed particles, and furthermore: (1)
It is characterized in that the mechanism for removing the gas phase generated particles is based on a chemical reaction, and also characterized in that (1) the chemical reaction is an oxidation reaction, and (2) the gas phase generated particles are It is characterized by the fact that the mechanism for removing it is based on a mechanical removal means, and ■ The hermetic coating material used is Kanibon, and the vapor phase generated particle layer deposited on the inner wall is a carbon particle layer. The reaction vessel has a double structure, with a diameter of 10 mm on the wall of the inner tube.
It is also characterized by a manufacturing device that has many pores with a diameter of 2 mm or less; It is also characterized in that an inert gas is introduced into the outer tube, and it is also characterized in that (1) oxygen is introduced into the outer tube. Hereinafter, the present invention will be explained in detail based on the drawings. FIG. 1 shows an optical fiber manufacturing apparatus of the present invention showing an example of the present invention. The reaction vessel body 1 has a double tube structure, with 10 being an inner tube and 1) being an outer tube. Raw material gas such as carbon-based gas is introduced from raw material gas introduction pipe 3, and unreacted gas, reaction products, etc. are discharged to the outside through reaction/waste gas discharge pipe 6. Hereinafter, when the llt elementary reaction is used as the removal method, the inner tube lO has a diameter of 10n or less, preferably 6n or less, more preferably 31 or less, for example 1n
Many pores are opened in the inner tube 10 and outer tube 1.
) Air or oxygen introduced from the oxygen introduction pipe 4 flows through the portion 9 between the two. Reference numeral 5 denotes an excess oxygen exhaust pipe, which can exhaust excess oxygen unnecessary for the oxidation reaction. 7.7゛ are the upper and lower seal gas introduction pipes, respectively. The spun high-temperature optical fiber 2 is fed into the reaction vessel 1, and between the raw material gas introduction pipe 3 and the reaction waste gas discharge pipe 6, the introduced raw material gas such as carbon-based gas is processed by chemical vapor deposition method or the like. The optical fiber 2 undergoes a thermal chemical reaction by means of
A hermetic coat is applied on top. At this time, a layer of gas-phase generated particles such as carbon particles deposited on the inner wall of the reaction vessel is oxidized by oxygen supplied to the portion 9 through the pores, becomes gaseous such as carbon dioxide, and is discharged together with the waste gas from the reaction. It is discharged from pipe 6. In this case, the oxygen introduction pipe 4 and/or the surplus @element discharge pipe 9
It is necessary to appropriately set the flow rate of oxygen or air by adjusting the amount of inflow and outflow of #element into the reactor. This is because if the amount of oxygen is too large, oxygen will enter the coating area and will consume the raw material. Furthermore, if the amount of oxygen is small, carbon particles cannot be removed efficiently. Considering the above, the diameter of the pores 8 is suitably about 0.5 to 1.5 days in diameter, but is not limited to this. Also, the amount of oxygen introduced. Although it depends on the amount of raw material gas input,
Approximately 100 cc/min to 5.01/min is appropriate. In addition, in order to increase the removal rate of the deposited particle layer, a heating device, such as a heating wire, may be installed around the manufacturing equipment as necessary.
An infrared lamp or the like may be installed. In the present invention, one of the mechanisms for removing the gas phase generated particle layer using such a chemical reaction, particularly an oxidation reaction, is adopted.
The deposited solid particle layer is quickly gasified and discharged to the outside without being deposited inside the reaction vessel. As a result, long-term continuous hermetic coating becomes possible. Moreover, FIG. 2 shows an optical fiber manufacturing apparatus of the present invention showing another specific example of the present invention. The basic structure of the reaction vessel 1 is the same as the case shown in FIG. However, as a mechanism for removing accumulated gas-phase solid particles,
The details involved in employing mechanical removal methods are the first.
This is different from the case shown in the figure. The inner tube 10 has many pores with a diameter of 5 mm.
In addition, an inert gas introduced from the inert gas introduction pipe 4' flows into a portion 9 between the inner tube 10 and the outer tube 1). In addition, the portion 9 is equipped with a scraping rod 12 for discharging the particle layer to the outside, and the scraping rod 12 is attached to a magnet 13.
By rotating it, the scraped out carbon particles and the like are discharged to the waste treatment tank 14. The waste treatment tank 14 is equipped with a filter or a combustion furnace, in which solid waste such as carbon particles or combustible gases are treated. A suction pump or the like is attached to this end, and the lower seal gas introduction pipe 7 is operated to maintain the exhaust system in a reduced pressure state. In this case, it is necessary to maintain the outer tube 1) at a lower pressure than the inner tube 10, so that the reaction gas, by-product gas, etc. flow from the inner tube 10 toward the outer tube 1) through the pores 8. . Therefore, the layer of gas-phase generated particles such as carbon particles generated in the reaction vessel is carried to the outer tube by the flow of such gas, and is carried by the inert gas flowing through the outer tube 1) to be treated as waste. It is guided to the tank 14. Here, in the upper part 15 of the reaction vessel, the temperature of the optical fiber 2 running is high and the concentration of the raw material gas is also high, which is an active region for the reaction. The source gas must be sufficiently supplied to the fiber surface. Therefore, it is desirable that the number of pores per unit area of the upper part 15 be reduced to prevent the raw material gas from escaping to the outside. On the other hand, the solid particles generated in the gas phase generated in the upper part 157 are deposited in the lower part 16 of the reaction vessel due to the downward flow, so the number of pores per unit area in this part 16 should be sufficiently large. It is necessary to make it possible to discharge to the outer tube side. Also, at this time, a layer of vapor-generated solid particles is deposited on the inner surface of the outer tube 1), but this accumulated particle layer is removed by rotating the spiral scraping rod 12 provided on the outer tube 1). (Due to such scraping and rotating operations, the solid particles generated in the gas phase float in the gas phase, but for the above-mentioned reasons, they remain within the outer tube, so they do not adversely affect the running optical fiber. As a result, long-term continuous hermetic coating becomes possible.

[Examples] The present invention will be specifically explained by the following examples, but these do not limit the misdemeanor of the present invention. Example 1 The following experiment was conducted using the optical fiber manufacturing apparatus shown in FIG. Using CZ Ha and CHCl3 as raw material gases, CHCl
He was used as the carrier gas in Example 3, and carbon was coated on the quartz fiber. Further, N2 was used as the upper noll gas, and air was used as the lower seal gas. The respective flow rate conditions are as follows. czHa: 100 cc/min, CHC13: 140 cc/min, seal Nz: 3.01/min, sealing air: 8.017 min, oxidation removal air: 1.017 min, and the drawing speed was 200 m/min. Ta. In addition, an infrared lamp was installed outside the reaction vessel for supplementary heating. Under these conditions, even after coating to about 100 +++ for about 8 hours, only a small amount of carbon particles remained in the reaction vessel, and it was possible to continue the process. Comparative Example: Under the same conditions as in Example 1 above, but without introducing air for oxidation removal, the deposited carbon particles came into contact with the optical fiber running in the reaction vessel after about 5 hours and about 60 km. It became impossible to continue coating. Example 2 The following experiment was conducted using the optical fiber manufacturing apparatus shown in FIG. Using Ct H4 and CHCl3 as raw material gases, CHCl,
He was used as a carrier gas, and carbon was coated on the quartz fiber. Furthermore, N2 was used as the upper seal gas and the gas introduced into the outer tube. The respective flow rate conditions are as follows. CtH-: 100cc/min, CHC13: 140cc/min, Seal Nt: 3.017 min, Seal air: 8.017 min, Outer tube introduction N2: 3, OR/min, and 8 wire drawing speed is 200 m/min I went there. Further, the pressure in the outer tube was set to be approximately 0.1 atm lower than that in the inner tube. In addition, solid carbon particles generated in the gas phase were discharged every 2 hours using a scraping rod. Even after approximately 1)00k coating was applied for approximately 8 hours under these conditions, only a small amount of carbon particles remained in the inner tube of the reaction vessel, and there was no problem in continuing the coating. .

【Effect of the invention】

As explained above, by using the mechanism for removing the layer of solid particles generated in the vapor phase according to the present invention, continuous coating can be performed for a long time, which is very useful for improving productivity.

[Brief explanation of the drawing]

1 and 2 are schematic diagrams of a hermetic coated optical fiber manufacturing apparatus of the present invention. l: Reaction vessel 2: Optical fiber 3: Raw material gas introduction pipe 4: Oxygen introduction pipe 4'': Inert gas introduction pipe 5: Surplus oxygen discharge pipe 6: Reaction/waste gas discharge pipe 7: Upper seal gas introduction pipe 7'' : Lower seal gas introduction pipe 8: Pore 9: Portion between inner and outer pipes 10: Inner pipe 1): Outer pipe 12: N extraction pipe 13: Mag, 14: Waste treatment tank 15. 16: Upper and lower parts of the reaction container

Claims (9)

[Claims] (1) After melting and spinning an optical fiber preform in a drawing furnace to make a bare fiber, the bare fiber is introduced into a reaction vessel, and a carbon-based raw material gas is introduced into the reaction vessel. An apparatus for producing a hermetically coated optical fiber in which a thin film coating layer is applied on a bare fiber by chemical vapor deposition, characterized by having a mechanism for removing vapor phase generated particles adhering to the inner wall of the reaction vessel, Manufacturing equipment for hermetic coated optical fiber. (2) The apparatus for manufacturing a hermetic coated optical fiber according to claim (1), wherein the mechanism for removing the gas phase generated particles adhering to the inner wall of the reaction vessel is based on a chemical reaction. (3) The apparatus for manufacturing a hermetic coated optical fiber according to claim (2), wherein the mechanism for removing the gas phase generated particles is based on an oxidation reaction. (4) The apparatus for producing a hermetic coated optical fiber according to claim (1), wherein the mechanism for removing the gas phase generated particles adhering to the inner wall of the reaction vessel is a mechanical removal means. (5) The hermetic coating material used is carbon,
2. The hermetic coated optical fiber manufacturing apparatus according to claim 1, wherein the vapor phase generated particle layer deposited on the inner wall is a carbon particle layer. (6) The reaction vessel has a double structure, with a diameter of 1 mm on the wall of the inner tube.
2. The hermetic coated optical fiber manufacturing apparatus according to claim 1, wherein a large number of pores of 0 mm or less are opened. (7) maintaining the outer tube in the reaction vessel at a lower pressure than the inner tube;
An apparatus for manufacturing a hermetic coated optical fiber according to any one of claims (4) and (6). (8) Claim (6), wherein an inert gas is introduced into the outer tube.
, (7). The hermetic coated optical fiber manufacturing apparatus according to any one of (7). (9) Claims (3) and (6) wherein oxygen is introduced into the outer tube.
), (7) the hermetic coated optical fiber manufacturing device.